Diatomic halogen (such as I2, Cl2, Br2, etc.) has traditionally been used to disinfect water. Diatomic chlorine, for example, is a widely exploited disinfectant for controlling or eliminating micro-organisms which may be present in water. A disadvantage of a sterilization regime which exploits diatomic halogen is that the regime may leave behind unacceptable (residual) levels of halogen in the water once sterilization is complete.
An iodine/resin product has, however, been proposed for use as a demand disinfectant, namely a disinfectant wherein iodine is released almost entirely on a demand-action basis. U.S. Pat. Nos. 3,817,860, 3,923,665, 4,238,477 and 4,420,590 teach such a demand disinfectant wherein iodine is the active disinfectant agent; the entire contents of each of these patents is incorporated herein by reference. In accordance with the teachings of these patents the resin product may be used without fear of introducing unacceptable concentrations of diatomic iodine into the water to be sterilized.
U.S. Pat. Nos. 3,817,860 and 3,923,665 teach an iodine/resin demand disinfectant which is the reaction product obtained by contacting a strong base anion exchange resin with a suitable source of triiodide ions. The reaction product is taught as being very stable in the sense that the amount of iodine (e.g. I2) released into water from the reaction product is sufficiently low that the water disinfected thereby is immediately ready for use, ie. as drinking water.
In accordance with the teachings of U.S. Pat. Nos. 3,817,860 and 3,923,665 the procedure for preparing the iodine/resin comprises forming a triiodide ion (solution or sludge) by dissolving diatomic iodine in a water solution of a suitable alkali metal halide (e.g. KI, NaI, . . . ). The triiodide solution is in particular taught as being made with a minimal (i.e. minor) water content just sufficient to avoid causing the I2 to crystallize out; see example 1 of U.S. Pat. No. 3,923,665. The resulting (solution) containing the triiodide ion is then contacted with the starting resin (under ambient conditions with respect to temperature (i.e. 25 to 30° C.) and pressure), the triiodide ions exchanging with the anion of the resin (e.g. exchange with chlorine, sulfate, etc.,). The starting resin is taught as being a porous granular strong base anion exchange resin having strongly basic groups in a salt form wherein the anion thereof is exchangeable with triiodide ions. In accordance with the teachings of the above prior art references contacting is continued until the desired amount of triiodide has reacted with the strongly basic groups such that bacterially contaminated water is disinfected when passed through a bed of the obtained resin. After a suitable contact time the iodine/resin is (water) washed to remove water-elutable iodine from the resin product.
However, as indicated in U.S. Pat. No. 4,238,477, it is difficult to use the procedures outlined in the two previously mentioned U.S. patents so as to obtain a homogeneous iodine/resin product containing only triiodide anions and wherein all of the active sites of the resin have been converted to triiodide ions.
Accordingly, U.S. Pat. No. 4,238,477 teaches an alternate process whereby the iodine/resin may be produced. In accordance with this alternate impregnation/contact process, a suitable resin in the iodide form (I−) is contacted with water comprising diatomic iodine (I2) in solution, the water being recycled between a source of a predetermined amount of diatomic iodine and the resin. The process as taught by this latter patent, however, is a relatively complicated system of pumps, vessels, heaters, etc.; by exploiting a fluidized bed, it in particular may lead to a significant degree of resin bead attrition, i.e. particle breakup.
The processes as taught in U.S. Pat. Nos. 3,817,860 and 3,923,665 are carried out at ambient temperature and ambient pressure conditions. U.S. Pat. No. 4,238,477 teaches that the contact may occur at a higher temperature such as 60 to 95° C. but that the temperature must be a non-boiling temperature (with respect to water); see column 3 lines 55 to 66.
The above referred to U.S. patents teach the use of the demand disinfectant iodinated resins for treating water; see also U.S. Pat. Nos. 4,298,475 and 4,995,976 which teach water purification devices or systems which exploit iodinated resins. None of these patents teaches the use of the iodinated resins for the purpose of sterilizing air.
It is also known to use iodine tincture for sterilising wounds. The sterilisation effect of iodine tincture is short lived; this means that the tincture must be reapplied on a regular basis to maintain the sterilisation effect. However, such solutions may also damage or destroy the tissue around the wound if applied too liberally and too often. Additionally, the direct application of such solutions to a lesion or wound is usually accompanied by a painful sensation.